The invention relates to a gas burner for use in a domestic cooking apparatus comprising a gas feed tube for introducing gas through an effluent member into a mixing tube and a burner cover near the outlet side of the mixing tube. With respect to dimensions gas burners are proportioned to the burner capacity. This depending upon the burner capacity for each type of gas burner, different sized components have to be manufactured and stocked. At the site of use, the burner capacity can only be changed by removing the whole burner and replacing it by another gas burner having a different capacity. This known practice is inconvenient because the production and storing of components are relatively expensive.